Hydraulic jack



April 2,. 1929.

H. c. SHEVLIN HYDRAULIC JACK Filed April 12. 1926 A? /i E; Z3 L A? %3 T 3% j- 4 v J 5 2a INVENTOR.

.2; W440 6T JZVZM/A ,5 BY

Jo 2; .93 ATTORNEY.

ignals.2,1959. v 'i1 7o7,491

UNITED STATES PATENT FFICE."

mmonn csxinvrfin', or'nmwnn, COLORADO, nssrenon, BY MESNE ASSIGNMENTS,

TO SHEVLIN HYDRAULIC JACK COMPANY, OF DENVER,

\ from or COLORADO.

coLonAno, A consona- HYDR-AUIJC JACK.

Application filed April 12, 1926. Serial N'o."101,267.- v

'have a minimum of moving parts, which 'will be positivesin operation, whiclrcan be actuated by .a very small arc of movement,

. and which can'be elevated or lowered by the operation of a single crank or lever.

Another object of the invention is to provide a jack in which the liquid under pressure never comes in contact with anyof the I packed shafts so that leakage is prevented.

A further object of the jack is to eliminate the necessity for atmospheric relief valves above the jack piston.

A still further Ob ect 1s to provide a posi-' tively operating, simply constructed valve for a jack of this character. 7

Other objects and advantages reside in the detail construction of the invention, which is designed for simplicity, economy and efficiency. These will become more apparent from the following description.

In thefollowing detailed description of the invention, reference is had to the accompanying drawing which forms a part hereof. Like numerals refer to like parts in'all views of the drawing and throughout the description.

i In the drawing /Fig. 1 .is a side elevation of the jack, look ing toward the extremity ofthe shaft.

reciprocated, by means of a piston rod-18. 'The pump washers 17 slide alongthepiston Fig. -2 is a vertical section through the jack, taken on the line 2-2, Fig. 1

Fig. 3 is a' horizontal section through the jack,'taken on the line 3 '3, Fig. 2.

uFigL 4 is a detail viewof the valve employed. I g v Thejack comprises a reservoir cylinder 10, mounted: in a base 11, adjacent to a. power cylinder-12. The cylinders 10 and 12 are threaded into the base 11 and are closed a-t'th-eir upper extremities by a cap casting 13 which is clamped against the cylinders by tie bolts 14.: The tie bolts pass through the'base '11 and are. provided, above the cap castingf13,'with nuts 15. S

Within the reservoir 10, also threaded ,into the base casting 11 is a pump cylinder 16, in which, slidable pump washers" 17 are rod 18, their movementbeing limited by a to' flow, through a port 30 in the flangeand through flutes 31 in the piston rod, into the pump cylinder. As the piston rod moves downwardly, the washers 17 will compress ,7 against the flange 29 effectively closing the port 30 to prevent return of the fluid. The cylinders 10 and 12. are filled with fluid, preferably Oil, to substantially-the level indicated in Fig. 2;

The piston rod terminates at its upper extremity in a rack 19 which is engage by a pinion 20 carried on an operatingshaft [21. In t-hepower cylinder 12, a piston 22 operates in connection with a. jack bar 23 which terminates in a jack socket 24. Communicating between the pump cylinder 16 and the power cylinder 12, is a pressure pas-. sage 25,- and communicating between the reservoir '10 and the pump cylinder 16,- isp a relief passage 26. The reliefpassage also-i communicates with the exterior of the jack for filling purposes, the exterior opening being closed by a plug 27. J I

In operation, the operating shaft 21- is rotated through a an are by means of any suitable operatinglever or crank (not shown) carried on, a sguared-extremity 32 upon the operating sha t 21. This rotation imparts a vertical reciprocation'to the piston rod lsthrough the medium of the rack and pinion 19 and 20 and causes thepump washers. 17 to force fluid into the passage 4 25 past a check valvb 33, which prevents its return to the pump cylinder. F rom" the passage 25, the fluid flows to the power cylinder 12 beneath the piston 22, forcing the latter 5 and the jack bar 23 upwardly. Thefluid above the piston (22 will rise and flow through the relief passage 26 to the reservoir 10. I I

The check valve 33 will maintain the piston 22 'at any desired height. When it is desired to lower the jack bar 23, the operat- ..ing shaft 21 is rotated so as to force the-pis-' ton rod 18 downwardly into contact with the stem 34 of the valve 33, thus,forcing it away from its seat and allowing the fluid to flow from'under the piston 22 into the pump cylinder 16 through grooves 35 formed therein, and around the pump washers 17 into, the reservoir 10. The downward motion of the piston rod 18 out of contact with the valve Samar.- 1 v 5 In the piston 22 a-relief valve 36 is provided, the stem of which contacts with the cap 13 when the piston-22 reaches the upward limit of its travel, thus allowing the fluid to tlpw through the piston 22 andprevent furt er pressure thereon. The valve 36 also acts to allow the 'fluid to pass through the piston 22 when the jack bar .23 is raised by an external pull. In this capacity, it acts simply as an auxiliary to the valve 33 for the jack bar 23 could be raised without thevalve 36 since it would draw fluid through the port 30, the pump cylinder 16, and the passage 25 and'discharge fluid from above the piston 22 through the passage 26 to the 20 power cylinder. This-flow, however, is r'ela tively restricted and the valve 36 is provided as an auxiliary to facilitate the upward movement of. the jack bar.

The piston rod 18 isoflset at'its connec- 1 tion with the rack 19, as shown in Fig. 2, so' as to allow the operating shaft 21 to be i placed upon'the center line of the jack. The cap 13 is provided with a rack track 37 which guides-the rack and maintains it always in contact with the pinion 20. The rack track r is entirely closed to prevent leakage. An opening is formed in the cap 13 around the operating shaft 21 sufficiently large to allow insertion of the pinion 20. This opening is i closed by a bearing 38 which also forms a gland for packing 39 around the operating shaft. Similar packing 40 is provided around the jack bar 23. p

It will be noted that the fluid which comes 40 in contact .wi'th any of the packing is not 1 under pressure, therefore the demand upon the packing is relatively light and leakage is effectively prevented.

It is desired to 'call attention tothe specific 4 construction of.the valves 33- and. 36, illus- 1 trated in detail in Fig. 4. Each of these valves havea semi-spherical head 41 carrying a threaded shank 34. A collar 43 is screwed onto the threaded shank 34 and maintains a washer 44, of relatively soft material, such as leather, in a counterbored seat in the-head 4L By this construction, the washer 44 always moves with the valve and cannot be forced from its seat by the fluid pressure. The washer 44 contacts with an annular projection 45 around the valve opening so that metal to metal conta'ctis avoided.

While a specific form of-the improvement 1 has been described and illustrated herein, it

is desired to be understood that the same 60.

may be varied, within the scope of the appended claims, without departing from the spirit of the invention. v

Having thus described the invention, what I claim and desire secured by Letters Patent is;.' i

1. In a pump cylinder having a piston rod adapted to reciprocate therein, means for providing a piston and check valve on said ro'd'comprising, a perforated flange formed on' said rodadjacent its one extremity, said extremity extending beyond said flange and pistonwashers slidably carried on said extremity and contacting with said pump cylinder and arranged to close said perforations at predetermined times, -said extremity being grooved so as to allow fluid to flow through said washers to said opening.

2. Means for actuating a puinp piston in a hydraulic jack comprising a rack operatively' so connectedto said piston; a stationary cap above said piston; a guide formed in said cap for said rack; a pinion having a shaft and adapted to mesh with said rack within said cap, there being an opening of suflicient size iw said cap to admit said pinion and a removable bearing adapted to-suppor t said shaft and close said opening'so as to allow removal'of said pinion through said' opening. i

' In testimony whereof, I aifix my signature.

HAROLD o. SHEVLIN. 

